Sperm DNA fragmentation

Among the infertility problems, 50% of the causes have a male origin, an analysis of the characteristics of his sperm is consequently essential to have a complete evaluation of the couple’s reproductive issues.

Approximately 10-15% of the sterile males, have normal seminal parameteres. In these cases, the origin of the male sterility might be due to defects in the membrane of the spermatozoa, or to environmental or genetic factors, amongst other cuases. These cannot be detected in the seminogram. In recent years, 25% of infertile males have elevated sperm DNA fragmentation levels, so that is presumed to be one of the possible causes of sterility.

An embryo to be viable needs the DNA of oocytes and spermataozoa to be intact. With regard to males, the easiest way to evaluate the quality of the sperm DNA is through its fragmentation level. The more elevated the levels are, the lower the fertilisation rate is. It has a negative impact on the embryonary quality and implantation rate.

Causes

There are different factors that can increase sperm DNA fragmentation levels, among these we can find the following:

High testicular temperature: high fever, varicocele or tight clothers can provoke an increase in testicular temperature, being the latter responsible of damaging the DNA.

Exposure to contaminants: the exposure to pesticides and to elevated environmental contamination can increase sperm DNA fragmentation.

Infections: some infections, for instance the infection caused by Chlamydia trachomatis, may affect semen quality and alter fragmentation levels.

Pharmaceutically-induceed: some antidepressants and antibiotics may increase sperm DNA fragmentation.

Smoking: smoking males have lower seminal quality, and it is known that smoking can increase the amount of sperm with fragmentation.

Treatment

Knowing the percentage of sperm with fragmented DNA will provide important information; to choose and assisted reproduction technique over others will depend on these levels. A percentage higher than 30% (depending as well on the technique used), will be regarded as pathological, performing an in vitro fertilisation or Intracytoplasmic sperm injection (ICSI) without inseminations (because it affects the success rate) are highly recommendable.

There are treatments with antioxydants, aimed to prevent and decrease fragmentation levels. The oral administration of antioxydants for 2-3 months can decrease oxydative stress and, therefore, sperm DNA. Several studies state that these treatments can reduce sperm fragmentation up to 20%.